Extremely high flow conditions are occurring across many areas of the Winnipeg River drainage basin in Ontario, Manitoba and Minnesota following record high precipitation since the start of April and early May. While flows in most natural rivers in the basin are dropping, many remain above previous all-time records. Forecasts indicate that inflows to all major lakes will rise for 2-3 days in response to the early week precipitation before falling again. Water levels will remain high for at least several weeks across most areas of the drainage basin even with dry conditions. Wet weather will prolong the duration of high water levels.
The current level of Lake of the Woods is 323.85 m (1062.5 ft), over 95th percentile level for this time of year. The average lake level rose by 9 cm (4 in) over past week. The lake level has risen above the 2014 peak of 323.78 m (1062.29 ft) and is below the record peak since regulation began of 324.31 m (1064.0 ft), set in July of 1950.
The level of Lake of the Woods is expected to rise by approximately 15-21 cm (6-8 in) over the next 7 days, the rate depending on the rainfall received on Monday and Tuesday as a series of thunderstorms and showers pass through the region. Continued rise beyond the 7-day forecast window is expected though the rate of rise should slow with drier weather. The timing of the peak cannot be predicted at this point and will depend on rainfall. Lake of the Woods water levels will likely remain above the Legislated Operating Range for many weeks. Record lake levels are possible and will depend on rainfall across the watershed in the next couple of weeks.
As the lake continues to rise, the level of the Winnipeg River between Kenora and Minaki is also expected to rise, though recently the level of Minaki has declined slightly, likely due to local tributary decline. The level rise over the next 7 days below Norman Dam and down to Minaki is expected to be 2-4 cm (1-2 in). This estimate is approximate given uncertainty in the local flows entering the river from tributary areas and the rainfall on Monday and Tuesday. The river will continue to gradually rise as long as Lake of the Woods continues to rise and daily fluctuations, up or down, are possible depending on how prevailing winds affect the local level of Lake of the Woods above the dams.
The current level of Lac Seul is 356.60 m (1169.9 ft), over 95th percentile level for this time of year. Lac Seul inflow is very high, resulting in a rise of 19 cm (8 in) over the past week. The lake is nearing the Flood Reserve, a range of water levels above the normal operating range defined by federal Order-in-Council that corresponds to a key level for dam safety concern for the Ear Falls dam. To avoid exceeding this range , additional outflow increases took place last weekend, with outflow now at 827m³/s. This is a very high outflow, last reached in 2008. Depending on the rainfall totals early this week, further increases are possible and will be announced on this Notice Board.
The main body of Lac Seul is expected to rise by 15-22 cm (6-9 in) over the next 7 days. Higher or lower rainfall amounts then currently forecast could see a rise outside of this forecast range.